EAVESDROPPING on Saturn鈥檚 rings is revealing secrets of the gas giant鈥檚 vast interior.
Conventional wisdom says that Saturn contains a solid central core surrounded by a roiling gassy-liquid mix of helium and hydrogen. 鈥淚t鈥檚 like a giant lava lamp 鈥� a slow boiling motion,鈥� says Jim Fuller of the Kavli Institute for Theoretical Physics in Santa Barbara, California. This flow was thought to keep everything evenly mixed.
But images captured by NASA鈥檚 Cassini spacecraft revealed steady vibrations at six different places in Saturn鈥檚 rings. Even though the rings are thousands of kilometres from Saturn鈥檚 surface, vibrations in them correspond to the way the planet squishes and contracts.
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Now Fuller has run a computer simulation of the vibrating rings. The results suggest that Saturn must have a stable, stratified layer, perhaps of liquid and rock, between the core and roiling exterior ().
This is the first time a seismological investigation has been conducted on another planet. Future work should reveal more about the structure and evolution of gas giants.
This article appeared in print under the headline 鈥淭o see inside Saturn, watch its rings鈥�
